This invention relates to a use of extrusion technology to manufacture an animal feed supplement comprising of at least one amino acid. In particular, the invention relates to a process comprising an extrusion step to provide a substantially free-flowing, non-dusting, granular amino acid feed supplement.
Amino acids, and in particular lysine, threonine and tryptophan, are used extensively in the animal feed industry. Traditionally, amino-acids used in the animal feed supplements are produced via fermentation, and purified through various methods of filtration, centrifugation, and crystallization. The final purified products are then dried by any suitable means, such as spray drying, fluid bed drying, or the like, and are then the dried product is packaged for sale.
The formulation of these products is an important consideration because large amounts, especially of lysine, have to be handled and mixed with other feed constituents. Such problems as dust and clumping need to be minimized while the free flowing characteristic of these products needs to be maximized. Hence, there is a need for a process for the manufacture of amino acid feed supplements which minimizes dust and clumping while still leading to an animal feed with free flowing characteristics.
A process in which an animal feed comprising pellets is produced is described in U.S. Pat. No. 5,622,710. The feed additive is typically pelletized using mixing tools. Expensive to operate high shear mixing tools are required to obtain dense pellets. In addition, a high shear mixing plant usually operates in batch mode. Hence, there is a need for a simpler process to produce a dense product and which can operate in batch, semi-continuous and continuous modes of operation.
In addition, a reliable operation of high shear mixing plant to provide a consistent high quality amino acid feed supplement is difficult to achieve. In particular, the operating parameters are not amenable to tight control. Thus, there is a need for a process in which the operating parameters are more amenable to tight control.
The modern day extruder can provide a dense cohesive product of uniform size, and also provide actions such as mixing, kneading and cooking. Additionally, these machines can greatly increase the bulk density in the final product. There is a concurrent need in the animal feed industry to increase bulk density in order to benefit from lower packaging, handling and storage costs. A density of 35 lbs/ft3 to 45 lbs/ft3 can greatly reduce costs by eliminating the need to pay freight and transportation costs for shipping essentially air in and around fluffy material, by reducing health hazards resulting from breathing air laden by light dusty material, and by reducing the need to clean an area where the fluffy material has settled.
Operating parameters in the extrusion process can be tightly controlled. For example, temperature in the extruder can be modulated using water or suitable heat transfer fluid in the heads surrounding the extruder barrels. The conveying rate, degree of mixing and the nature and extent of compressive forces applied to the extrudable mixture during the extrusion process are controlled by screw configuration. In turn, a screw configuration is controlled by the flight distance, the use of shear locks, conical elements and where appropriate reverse flighting. Moisture, often in the form of steam, can be adjusted by direct injection into the extruder barrels of the extruder.
The use of extrusion technology is quite widespread in the food and confectionery industry and has been in commercial use as early as the 1920""s in the manufacture of pasta. Examples of publications include: Journal Of The American Oil Chemists Society, 1983, Vol.60, No.4, pp.750-751; Confectionery Production, 1985, Vol.51, No.9, p.492; Abstracts Of Papers Of The American Chemical Society, 1992, Vol.204, No.Pt1, pp.149-AGFD; Journal Of Food Engineering, 1996, Vol.30, No.3-4, Pp.449-467.
U.S. Pat. No. 5,186,970 describes a food extrusion method comprising forcing a food material through a die. A food forming apparatus is also described which comprises a food extrusion zone to an extrusion end of which a die having an orifice shape corresponding to the shape of a final food product is fitted, and a suction chamber which encloses the outside of the die and whose inside is evacuated to a reduced pressure by a vacuum means.
U.S. Pat. No. 5,034,232 describes the preparation of a flavored imitation meat protein material having a fibrous structure and a fried product thereof. The process comprises treating an aqueous mixture of a protein raw material and a flavor material with a twin-screw extruder under high temperature and pressure, extruding through a die with the expansion of the extruded material, and optionally drying the extruded material.
U.S. Pat. No. 5,290,560 describes the preparation of granules for the feeding or treatment of ruminants. The granules comprise active materials and a meltable binder such as a polyethylene wax. The granules are designed for trans-rumen passage without incurring degradation. The process comprises extruding a mixture through one or more dies. The active materials include amino acids such as methionine, lysine or its salts, phenylalanine, histidine, arginine, tyrosine and tryptophan, and medicoments such as vitamins, antibiotics, anti-parasitic agents and proteins. The granules of active materials are intended for the feeding or treatment of ruminants.
U.S. Pat. No. 5,077,074 describes the preparation of cookie products involving extrusion heating and wire cutting. The process comprises adding cookie ingredients to a cooker extruder to form a heat treated mass, which is admixed with additional cookie ingredients to form a dough-like cookie mixture. The cookie mixture is subsequently wire cut into individual pieces.
Accordingly, an object of this invention is to provide a process for the manufacture of amino acid feed supplements which minimizes dust and clumping while still leading to an animal feed with free flowing characteristics. A more particular object is to provide a simpler process to produce a dense amino acid feed supplement. Another object is to provide a dense amino acid feed supplement on a batch, semi-continuous or continuous basis. Yet another object is to provide a process in which the operating parameters are more amenable to tight control.
Other objects features and advantages of the present invention will be apparent from the following detailed description of the invention.
This invention generally entails a method for producing a substantially free-flowing, non-dusting, granular amino acid feed supplement comprising the steps of mixing at least one substantially pure amino acid to provide an extrudable mixture and then extruding the extrudable mixture to provide at least one noodle.
In one embodiment, at least one noodle is segmented and dried to provide substantially dry segments. Then, milling the substantially dried segments provides granules. Sieving the granules provides a substantially free-flowing, non-dusting, granular amino acid feed supplement, preferably in a size range between about 177 micron and 1190 micron.